001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry.wml;
016    
017    import org.apache.hivemind.HiveMind;
018    import org.apache.tapestry.AbstractComponent;
019    import org.apache.tapestry.IMarkupWriter;
020    import org.apache.tapestry.IRequestCycle;
021    
022    /**
023     * The do element provides a general mechanism for the user to act upon the
024     * current card, in other words a card-level user interface element. The
025     * representation of the do element is user agent dependent and the author must
026     * only assume that the element is mapped to a unique user interface widget that
027     * the user can activate. For example, the widget mapping may be to a
028     * graphically rendered button, a soft or function key, a voice-activated
029     * command sequence, or any other interface that has a simple "activate"
030     * operation with no inter-operation persistent state. The do element may appear
031     * at both the card and deck-level.
032     * 
033     * @author David Solis
034     * @since 3.0
035     */
036    
037    public abstract class Do extends AbstractComponent
038    {
039    
040        /**
041         * @see AbstractComponent#renderComponent(IMarkupWriter, IRequestCycle)
042         */
043    
044        protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle)
045        {
046            boolean render = !cycle.isRewinding();
047    
048            if (render)
049            {
050                writer.begin("do");
051    
052                writer.attribute("type", getType());
053    
054                String label = getLabel();
055                if (HiveMind.isNonBlank(label)) writer.attribute("label", label);
056    
057                renderInformalParameters(writer, cycle);
058            }
059    
060            renderBody(writer, cycle);
061    
062            if (render) writer.end();
063        }
064    
065        public abstract String getType();
066    
067        public abstract String getLabel();
068    }